RU2398794C2 - Composition of propylene polymers for hot moulding - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: composition contains 60-90 wt % copolymer of propylene and ethylene which contains 0.5-1.5 wt % ethylene links; and 10-40 wt % copolymer of propylene which contains 20-28 wt %. Flow rate of the molten composition of propylene polymers is less than 10 g/10 min in accordance with ISO 1133 (230C, 2,16 kg). ^ EFFECT: obtained compositions are suitable for producing hot moulded articles and articles made through blow moulding which have good mechanical properties combined with good optical properties. ^ 5 cl, 2 tbl, 4 ex

Description

The present invention relates to compositions of thermoplastic polyolefins and to products derived from them. In particular, the compositions described hereinbelow are suitable for use in the manufacture of hot formed articles having good mechanical properties in combination with good optical properties.

European patent application WO 01/92406 describes compositions of thermoplastic polyolefins exhibiting improved toughness and good optical properties containing (A) from 70 to 90% of a random copolymer of propylene and ethylene containing from 1 to 6% ethylene, characterized by a fraction level insoluble in xylene at room temperature, not less than 93% (wt.), and (B) from 10 to 30% of a copolymer of propylene and ethylene containing from 8 to 18% ethylene, characterized by a specific ratio between percentage soda neigh in the copolymer composition (B) and the level of content of ethylene therein. Mentioned compositions exhibit a balance between mechanical and optical properties that is excellent for blow molding applications, however, this balance is less satisfactory for applications that require good toughness characteristics at low temperatures.

Good characteristics of the low temperature toughness of a thermoplastic polyolefin are described in EP 1448622. The compositions mentioned also have a low content of the fragment extracted in hexane; contain a propylene copolymer characterized by a xylene insoluble fraction of not less than 85% (wt.), and a propylene copolymer containing 8-40% (wt.) alpha olefin, and exhibit a (MFR L) 3- 30 g / 10 min. The aforementioned values (MFR L) are obtained by peroxide decomposition for a precursor composition having a lower “MFR L” value. However, peroxide decomposition leads to an increase in the “Yellowing Index” of the polyolefins, and thus the resulting propylene polymer compositions, usually white, become yellowish. In addition, peroxide decomposition usually results in foul-smelling chemical compounds, which may hamper the use of cracked polyolefins in food applications such as freezer packaging.

Therefore, the aim of the present invention is to provide new compositions of thermoplastic polyolefins that detect a good balance of flexibility and low temperature toughness characteristics with desired flow, while at the same time preserving good optical properties and preventing problems associated with peroxide decomposition.

The present invention provides propylene polymer compositions containing (mass percentages correlated to total A + B):

(A) 60-90% (wt.) Copolymer of propylene and ethylene containing less than 2.5% (wt.), Preferably less than 2, and more preferably in the range from 0.5 to 1.5% ( wt.) ethylene units; and

(B) 10-40% (wt.) Of a propylene copolymer containing from 15 to 35% (wt.), Preferably from 18 to 30% (wt.), And more preferably from 20 to 28% (wt.) Of ethylene units ,

wherein said polymer composition is characterized by a melt flow rate of less than 10 g / 10 min, preferably less than 5, and more preferably in the range of 0.5-4 g / 10 min, in accordance with ISO 1133 (230 ° C, 2.16 kg).

Preferably, the propylene polymer compositions of the invention contain 70-88%, more preferably 75 to 88% (wt.) Of component (A) and 12-30%, preferably 12-25% (wt.) Of component (B).

In a preferred embodiment, component (A) from the propylene polymer compositions of the present invention is characterized by a level of fraction soluble in xylene at 25 ° C. of less than 3.5% by weight. The xylene soluble fraction is determined in accordance with the method described hereinafter.

In the case of the most preferred propylene polymer compositions of the present invention, the meaning of the equation

XS (tot) × [C2 (tot) - C2 (A)] (1)

is a value greater than or equal to 35, preferably greater than 65, where C2 (A) represents the molar percentage of comonomers in the copolymer (A), C2 (tot) represents the total molar percentage of comonomers in the composition of propylene polymers, and XS (tot) represents the total level of the content of the fraction soluble in xylene in the composition of propylene polymers (mass percent).

Surprisingly, it was found that if the value of equation (1) is greater than the aforementioned critical values, then the propylene polymer compositions of the present invention will exhibit a favorable balance of stiffness (flexural modulus), resistance to impact (expressed through the transition temperature plastic fracture / brittle fracture) and transparency (turbidity). The molecular weight distribution for the propylene polymer composition of the invention, determined in accordance with the method proposed below, is a value greater than 3.5, and preferably greater than 4.

The propylene polymer compositions of the invention are typically characterized by a bending modulus of less than 1200 MPa, preferably in the range of 750 to 1000 MPa, and a plastic break / brittle fracture transition temperature of not more than 5 ° C., preferably in the range of - 20 to 0 ° C. In addition, said propylene polymer compositions are typically characterized by a turbidity value, measured for a 1 mm plate, not greater than 40%, preferably not more than 30%.

The intrinsic viscosity of component (B) is usually in the range of 0.5 dl / g to 3.5 dl / g, preferably 0.8 dl / g to 2.0 dl / g.

Compositions of the propylene polymers of the invention are characterized by a yellowing index value less than 1.0, and in addition, they are characterized by a low content of the fraction extracted in hexane, less than 6.0% (wt.), Preferably less than 5, 0% (wt.).

The propylene polymer compositions of the present invention can be obtained by stepwise polymerization in at least two stages, each subsequent polymerization stage being carried out in the presence of a polymeric material obtained in the course of the immediately preceding polymerization reaction, where copolymer (A) is usually obtained, at least one first polymerization stage, and the copolymer (B) is usually obtained in at least one second polymerization stage.

Preferably, each polymerization step is carried out in the presence of a highly stereospecific heterogeneous Ziegler-Natta catalyst. Ziegler-Natta catalysts suitable for use in the preparation of the propylene polymer compositions of the invention include a solid catalyst component containing at least one titanium compound having at least one titanium-halogen bond and at least one electron donor a compound (internal donor), wherein both compounds are supported on a support in the form of magnesium chloride. Ziegler-Natta catalyst systems further include an organoaluminum compound as a substantial cocatalyst and optionally an external electron donor compound.

Suitable catalyst systems are described in European patents EP 459777, EP 361494, EP 728769, EP 1272533 and in international patent application WO 00/63261.

Preferably, the solid component of the catalyst contains Mg, Ti, halogen and an electron donor selected from succinates described by formula (I):

where the radicals R ₁ and R ₂ identical to each other or different from each other, represent a C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; radicals R ₃ to R ₆ , identical to each other or different from each other, are hydrogen or a C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group optionally containing heteroatoms, and radicals from R ₃ to R ₆ , which are bonded to the same carbon atom, can be bonded to each other to form a ring.

R ₁ and R _{2 are} preferably C ₁ -C ₈ alkyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups. Particularly preferred are compounds in which R ₁ and R ₂ are selected from primary alkyls and, in particular, branched primary alkyls. Examples of suitable R ₁ and R ₂ groups for use are methyl, ethyl, n-propyl, n-butyl, isobutyl, neopentyl, 2-ethylhexyl. Especially preferred are ethyl, isobutyl and neopentyl.

One of the preferred groups of compounds described by formula (I) is a group in which R ₃ to R ₅ radicals are hydrogen and R ₆ is a branched alkyl, cycloalkyl, aryl, arylalkyl and alkylaryl radical containing from 3 to 10 carbon atoms. Another preferred group of compounds, including those described by formula (I), is a group in which at least two radicals R ₃ to R ₆ differ from hydrogen and are selected from C ₁ -C ₂₀ a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups optionally containing heteroatoms. Particularly preferred are compounds in which two radicals other than hydrogen are attached to the same carbon atom. In addition, compounds in which at least two radicals other than hydrogen are attached to different carbon atoms, that is, R ₃ and R ₅ or R ₄ and R _6, are also particularly preferred.

According to a preferred method, a solid catalyst component can be obtained by reacting a titanium compound of the formula Ti (OR) _ny X _y , where n is the valence of titanium and y is a number in the range from 1 to n, preferably TiCl ₄ and magnesium chloride formed from the adduct of the formula MgCl ₂ • pROH, where p is a number in the range from 0.1 to 6, preferably from 2 to 3.5, and R is a hydrocarbon radical containing 1-18 atoms carbon. The adduct, if appropriate, can be obtained in a spherical form by mixing alcohol and magnesium chloride in the presence of an inert hydrocarbon immiscible with the adduct when carrying out the operation under stirring at the melting point of the adduct (100-130 ° C). After this, the emulsion is rapidly subjected to rapid cooling, thereby causing the solidification of the adduct in the form of spherical particles. Examples of spherical adducts obtained in accordance with this technique are described in US 4,399,054 and US 4,469,648. The adduct thus obtained can be directly reacted with the Ti compound, or it can first be subjected to thermally controlled dealcoholation (80-130 ° C) in order to obtain an adduct in which the number of moles of alcohol is generally less than than 3, preferably in the range of 0.1 to 2.5. The reaction with compound Ti can be carried out by suspending the adduct (subjected to dealcoholation or as such) in cold TiCl ₄ (generally at 0 ° C); the mixture is heated up to 80-130 ° C and maintained at this temperature for 0.5-2 hours. Processing using TiCl ₄ can be carried out one or more times. An internal donor may be added during treatment using TiCl ₄ , and treatment with an electron-donor compound may be repeated one or more times. In the General case, the succinate described by the formula (I) is used in a molar ratio with MgCl ₂ in the range from 0.01 to 1, preferably from 0.05 to 0.5. The preparation of spherical-shaped catalyst components is described, for example, in European patent application EP-A-395083 and in international patent application WO 98/44001. The solid catalyst components obtained in accordance with the aforementioned method exhibit a specific surface area (determined according to the Brunauer-Emmett-Teller method) generally in the range from 20 to 500 m ² / g, and preferably from 50 to 400 m ² / g, and the total porosity (determined according to the Brunauer-Emmett-Teller method), greater than 0.2 cm ³ / g, preferably in the range from 0.2 to 0.6 cm ³ / g The porosity (determined by the method using Hg), due to the presence of pores with a radius of up to 10,000 U, is generally in the range from 0.3 to 1.5 cm ³ / g, preferably from 0.45 to 1 cm ³ / g .

The organoaluminum compound is preferably an alkyl-Al compound selected from trialkylaluminum derivatives such as, for example, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum. It is also possible to use mixtures of derivatives of trialkylaluminum and alkylaluminum halides, alkylaluminum hydrides or alkylaluminum sesquichlorides, such as AlEt ₂ Cl and Al ₂ Et ₃ Cl ₃ .

Preferred compounds of external electron donors include silicon compounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines, heterocyclic compounds, and in particular 2,2,6,6-tetramethylpiperidine, ketones and 1,3-diethers . Another class of preferred compounds of external donors is a class of silicon compounds described by the formula R _a ⁵ R _b ⁶ Si (OR ⁷ ) _c , where a and b are integers in the range from 0 to 2, c is an integer in the range from 1 to 3, and the sum (a + b + c) is 4; R ⁵ , R ⁶ and R ⁷ are alkyl, cycloalkyl or aryl radicals containing 1-18 carbon atoms and optionally containing heteroatoms. Particularly preferred are methylcyclohexyl dimethoxysilane, diphenyldimethoxysilane, methyl tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane and 1,1,1-trifluoropropyl-2-ethylpiperidyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyl dimethyldimethyl dimethyl dimethyldimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimethyl dimeth and lI in? In. The compound of the external electron donor is used in such an amount as to obtain a molar ratio between the organoaluminum compound and said electron-donor compound in the range from 0.1 to 500.

The polymerization process can be implemented in the gas phase and / or in the liquid phase, in continuous or batch reactors, such as fluidized bed reactors or slurry reactors. For example, to obtain propylene polymer (A), polymerization can be carried out in the liquid phase using liquid propylene as a diluent, while the copolymerization step to obtain the propylene copolymer fraction (B) is carried out in the gas phase, without intermediate stages, with the exception of incomplete degassing for removal of monomers. Alternatively, all stages of stepwise polymerization can be carried out in the gas phase. The reaction time, temperature and pressure for the polymerization steps are not critical, however, the temperatures for obtaining fractions (A) and (B), which may be the same or different, are usually in the range from 50 ° C to 120 ° C. The polymerization pressure is preferably in the range from 0.5 to 12 MPa if the polymerization is carried out in the gas phase. The catalyst system can be precontacted (prepolymerized) with small amounts of olefins. The molecular weight of the propylene polymer composition is controlled using known regulators, such as hydrogen.

In accordance with a preferred embodiment, the propylene polymer (A) is produced by a gas phase polymerization process implemented in at least two interconnected polymerization zones. Said polymerization process is described in European patent EP 782587.

The method is implemented in the first and second communicating polymerization zones, into which propylene and ethylene or propylene and alpha olefins are fed in the presence of a catalyst system, and from which the obtained polymer is discharged. The growing polymer particles flow through the first of the mentioned polymerization zones (upstream reactor) under rapid fluidization conditions, leave the first polymerization zone and enter the second of the mentioned polymerization zones (downstream reactor), through which they flow in a sealed form under the action of forces of gravity leave the second polymerization zone and re-enter the first polymerization zone, thus participating in the formation of the polymer circulation cycle between smelling polymerization zones. In general, rapid fluidization conditions in the first polymerization zone are formed by feeding a mixture of gaseous monomers below the point of reintroduction of the growing polymer into said first polymerization zone. The feed rate of the transporting gas to the first polymerization zone is greater than the transport rate under operating conditions, and is usually in the range of 2 to 15 m / s. In the second polymerization zone, which the polymer flows in a compacted form under the action of gravity, high values of the density of the solid phase are achieved, which approach the values of the bulk density of the polymer; thus, a positive pressure increase can be obtained in the direction of flow, so that it is possible to reintroduce the polymer into the first reaction zone without the aid of mechanical means. Thus, a circulation cycle is formed in the “loop”, which determines the pressure balance between the two polymerization zones and the loss of pressure introduced into the system. Optionally, in the polymerization zones, the presence of one or more inert gases, such as nitrogen or an aliphatic hydrocarbon, is maintained in such quantities that the sum of the partial pressures of the inert gases is preferably in the range from 5 to 80% of the total gas pressure. Operating parameters, such as, for example, temperature, are those that are common in gas phase polymerization of olefins, for example, in the range from 50 ° C to 120 ° C. The method can be implemented at a working pressure in the range from 0.5 to 10 MPa, preferably from 1.5 to 6 MPa. Preferably, the various catalyst components are fed into the first polymerization zone at any point in said first polymerization zone. However, they can also be fed anywhere in the second polymerization zone. To control the molecular weight of the growing polymer, polymerization degree regulators known in the art, in particular hydrogen, can be used.

In a second step of a particularly preferred polymerization process in a commonly used gas phase fluidized bed reactor, a propylene / ethylene copolymer (B) is prepared in the presence of a polymeric material and a catalyst system coming from a previous polymerization step. The polymerization mixture is discharged from the downstream reactor to a gas and solid phase separator, and then fed to a gas-phase fluidized-bed reactor operating under commonly used conditions of temperature and pressure.

The propylene polymer compositions of the present invention can also be obtained by separately producing the said copolymers (A) and (B) by operation using the same catalysts and essentially under the same polymerization conditions as previously illustrated and subsequently mechanical mixing said copolymers in a molten state using conventional mixing equipment similar to twin screw extruders.

The propylene polymer compositions of the present invention, in addition, may contain additives commonly used in the field of application of polyolefins, such as antioxidants, light stabilizers, nucleating agents, additives that prevent the formation of acids, dyes and fillers.

The main fields of application of the propylene polymer compositions of the invention are the production of sheets for hot forming applications and the production of products by the blow molding technique. Obtained by the method of hot molding products containing the composition of the propylene polymers of the invention demonstrate good flexibility and good toughness at low temperatures, and they are also given good transparency. Due to the low content of the fraction extracted in hexane in the polyolefin compositions of the invention and the absence of foul-smelling end products of peroxide decomposition, the products thus obtained are particularly well suited for use in food applications, in particular in the case of glasses and boxes, used for packaging food for the freezer.

The following examples are provided to illustrate and not to limit the present invention.

Examples

Data on the materials of propylene polymers were obtained in accordance with the following methods.

Xylene soluble fraction

2.5 g of polymer and 250 ml of o-xylene are introduced into a glass flask equipped with a refrigerator and a magnetic stirrer. The temperature is increased over 30 minutes up to the boiling point of the solvent. After that, the thus obtained solution was kept under reflux and stirring for another 30 minutes. Then the closed flask is kept for 30 minutes in a bath with ice and water, and also for 30 minutes in a thermostatic water bath at 25 ° C. The solid phase thus obtained is filtered on quick filter paper and the filtered liquid is separated into two 100 ml aliquots. One aliquot of the filtered liquid with a volume of 100 ml is poured into a pre-weighed aluminum container, which is heated on a heating plate in a stream of nitrogen to remove the solvent by evaporation. After that, the container is kept in an oven at 80 ° C in vacuum until a constant weight is achieved. The residue is weighed to determine the percentage of polymer soluble in xylene.

Comonomer Level (C2)

By IR spectroscopy

The comonomer content in component B is determined for the precipitated “amorphous” polymer fraction. The precipitated “amorphous” fraction is obtained as follows: 200 ml of acetone are added to one of the aliquots of the filtered liquid obtained as described above with a volume of 100 ml with vigorous stirring. Precipitation should be complete, as evidenced by the pure separation of the solid phase and the solution. The solid phase thus obtained is filtered off on a tared metal strainer and dried in a vacuum oven at 70 ° C. until a constant weight is achieved.

The molar ratio for the gases of the feedstock is determined by gas chromatography.

The melt flow rate (MFR) is determined in accordance with ISO 1133 (230 ° C, 2.16 kg).

The intrinsic viscosity is determined in tetrahydronaphthalene at 135 ° C.

The number average molecular weight and the weight average molecular weight

The molecular weights and molecular weight distributions of Mw / Mn were determined by gel permeation chromatography (GPC) at 145 ° C in 1,2,4-trichlorobenzene using Waters GPC apparatus 150C. Data was evaluated using Win-GPC software from HS-Entwicklungsgesellschaft für wissenschaftliche Hard- und Software GmbH, Ober-Hilbersheim. Columns were calibrated using polypropylene standards, characterized by molecular weights in the range from 100 to 107 g / mol.

Flexural modulus is determined in accordance with ISO 178.

Tensile stress at yield strength and tensile tensile stress are determined in accordance with ISO 527.

Elongation at yield strength and fracture is determined in accordance with ISO 527.

Izod impact strength is determined in accordance with ISO 180 / 1A.

Transition temperature plastic fracture / brittle fracture (ductility / brittleness)

In accordance with this method, impact resistance on two axes is determined as a result of striking using an automatic, computerized hammer hammer.

Round test specimens are obtained by cutting using a round hand punch (38 mm in diameter). They are conditioned for at least 12 hours at 23 ° C and 50% relative humidity, and then placed for 1 hour in a thermostated bath at the test temperature. During striking with a hammer hammer (5.3 kg, a hemispherical punch with a diameter of 1/2 ''), a force-time curve is recorded on a circular sample resting on a circular support. The machine used is the CEAST 6758/000 type model no.2 installation.

The ductility / brittleness transition temperature is the temperature at which 50% of the samples undergo brittle fracture during the aforementioned impact test.

The measurement plates for the ductility / brittleness transition having dimensions of 127 × 127 × 1.5 mm are obtained in accordance with the following method.

The injection machine is a Negri Bossi ™ type machine (NB 90) with a clamping force of 90 tons. The shape is a rectangular plate (127 × 127 × 1.5 mm).

The main technological parameters are given below.

Back pressure (bar): twenty Injection Time (sec): 3 Maximum casting pressure (MPa): fourteen Casting Hydraulic Pressure (MPa): 6-3 Hydraulic pressure at the first exposure (MPa): 4 ± 2 First exposure time (sec): 3 Hydraulic pressure at the second exposure (MPa): 3 ± 2 Second exposure time (sec): 7 Cooling Time (sec): twenty Form temperature (° C): 60

The melt temperature is in the range from 220 to 280 ° C.

Turbidity (for 1 mm plate)

According to the method used, samples with dimensions of 5 × 5 cm are cut molded plates with a thickness of 1 mm, and the turbidity value is measured using a Gardner photometric apparatus connected to a Hazemeter type UX-10 turbidity meter or an equivalent device having a light source GE 1209 with filter "C". To calibrate the instrument, reference samples with a known turbidity are used. The plates to be tested are prepared in accordance with the following method. The plates with dimensions of 75 × 75 × 1 mm are formed using a GBF Plastiniector G235 / 90 injection machine with a force of 90 tons under the following process conditions.

Screw rotation speed: 120 rpm Back pressure: 10 bar Melt Temperature: 260 ° C Injection time: 5 sec Shutter Speed Pressure: 50 bar Exposure pressure of the first stage: 30 bar Second stage pressure: 20 bar Exposure Pressure Profile: First stage 5 sec Second stage 10 sec Cooling time: 20 sec Form water temperature: 40 ° C

The content of the fraction extracted in hexane

The content of the fraction extracted in hexane is determined in accordance with the modified method of the Office for the Control of the Quality of Food, Drugs and Cosmetics (federal registration, title 21, Chapter 1, part 177, section 1520, s. Annex B) for the polymer, molded in the form of positions with a thickness of 100 μm.

The melting temperature, melting enthalpy and crystallization temperature are determined by the DSC method with a temperature change of 20 ° C per minute.

Yellowing rate

The yellowing index (YI) is determined by direct measurement of the color coordinate granules in the X, Y, and Z three-coordinate system using a three-color colorimeter capable of estimating the color deviation of an object from a predefined standard white color in the yellow direction in the range of dominant wavelengths from 570 up to 580 nm. The geometric characteristics of the equipment should make it possible to observe reflected light in perpendicular fields of view for two rays of light that fall on the sample at an angle of 45 °, and at an angle of 90 ° to each other, leaving the Source C device in accordance with the standard of the International Commission for lighting. After calibration, the glass container is filled with the granules to be tested, and the coordinates X, Y, Z are obtained to calculate the yellowing index in accordance with the following equation:

YI = 100 * (1.274976795 * X - 1,058398178 * Z) / Y

Examples 1-4

The Ziegler-Natta catalyst was prepared in accordance with Example 5, lines 48-55 of European patent EP728769. Triethylaluminum (TEAL) was used as a cocatalyst, and dicyclopentyl dimethoxysilane was used as an external donor, and the weight ratios are shown in Table 1.

The propylene polymer compositions of the examples were prepared as part of a two-stage polymerization process, where the copolymer (A) was obtained in the first polymerization step by feeding monomers and a catalyst system to a gas-phase polymerization reactor, including two interconnected polymerization zones — an upstream reactor and a reactor with a downward flow, as described in European patent EP 782587. The polymerization mixture was discharged from the aforementioned reactor, transported to a gas and solid phase separator and filled erizovanny material forwarded normally used in a gas phase fluidized bed reactor, where the obtained propylene / ethylene copolymer (B). Operating conditions are shown in table 1.

The polymer particles coming from the second polymerization step were subjected to steam treatment to remove unreacted monomers and dried.

The additives shown in Table 2 were added to the propylene polymer compositions and extruded in a Berstorff twin screw extruder (L / D = 33) under the following working conditions.

Supply section temperature: 190-210 ° C Melt Temperature: 240 ° C Extrusion head section temperature: 230 ° C Consumption: 16 kg / hour Rotational speed: 250 rpm

The properties measured for the samples are collected in table 2.

Table 1 EXAMPLE one 2 3 four TEM (triethylaluminium) / donor g / g 6 6 6 6.5 TEM / catalyst g / g 5 5 5 5 Component A Temperature ° C 78 78 78 78 Pressure MPa 27 27 27 27 H2 / C3 mol / mol 0.0020 0.0035 0.0025 0.0025 Mfr g / 10 ' 0.75 1.10 0.9 0.93 C2 (A) % (wt.) 1.15 1.00 1.10 0.90 X.S. (xylene soluble fraction) % (wt.) 2 1.9 2.6 2 Component B Temperature ° C 80 80 80 80 Pressure bar 19 19 19 19 The content of the component in the mixture % (wt.) 22 eighteen 16 21 C2 (B) % (wt.) 22 22 24 19 C2- / C2- + C3- mol / mol 0.11 0.11 0.13 0.10

Final composition Mfr g / 10 ' 1,5 1.3 1.3 1.4 C2 (tot) % (wt.) 5.65 5.00 4.80 4.70 XS (tot) % (wt.) 19.5 15,5 15.3 16.5 X.S.I.V. (intrinsic viscosity of xylene soluble fraction) dl / g 1.36 1.46 1.26 1.41 table 2 EXAMPLE one 2 3 four The composition of the granules Irganox 1010 % (wt.) 0.05 0.05 0.05 Irgafos 168 % (wt.) 0.1 0.1 0.01 Calcium stearate % (wt.) 0.04 0.04 0.04 0.05 Millad 3988 % (wt.) 0.18 0.18 0.18 0.18 Irganox B225 % (wt.) - - - 0.150 OV 22 AT oil % (wt.) - - 0.05 0.05 Characteristics Flexural modulus MPa 825 940 1035 1010 Tensile stress at yield strength MPa 24.4 24.4 28.3 27.1 Elongation at yield strength % 21.3 21.3 16.1 16.9 Tensile stress MPa 26.5 26.5 21.7 21,4 Izod impact strength at 23 ° C kJ / m ² 67.3 66 62.3 NB Izod impact strength at 0 ° C kJ / m ² 44.1 36.8 24.0 30,0 Izod Impact Strength at 20 ° C kJ / m ² 3.4 3,1 2,4 2.9 Transition temperature ductility / fragility ° C - 19.6 - 9.3 - 5.8 - 7 Turbidity (for 1 mm plate) % 16.8 15.8 15.1 15.3

Irganox 1010 is a long-acting phenolic antioxidant supplied by CibaSpecialty.

Irganox B225 supplied by Ciba.

Irgafos 168 is a stabilizer supplied by Ciba.

Millad 3988 is a nucleating agent supplied by Milliken Europe.

GMS 90 is an antistatic agent supplied by Ciba Specialty Chemicals S.p.A.

Claims (5)

1. The composition of propylene polymers suitable for the production of thermoformed products and products obtained by the method of blow molding, containing (mass percentages are related to the total amount of A + B):
(A) 60-90 wt.% A copolymer of propylene and ethylene containing from 0.5 to 1.5 wt.% Ethylene units; and
(B) 10-40 wt.% A propylene copolymer containing from 20 to 28 wt.% Ethylene units,
wherein said polymer composition is characterized by a melt flow rate of less than 10 g / 10 min, in accordance with ISO 1133 (230 ° C, 2.16 kg), and a bending modulus ranging from 750 to 1000 MPa . 2. The propylene polymer composition according to claim 1, where the melt flow rate is less than 5 g / 10 min, in accordance with ISO 1133 (230 ° C., 2.16 kg). 3. The propylene polymer composition according to any one of claims 1 and 2, containing 70-88 wt.% Component (A) and 12-30 wt.% Component (B). 4. Thermoformed product containing a composition of propylene polymers according to any one of claims 1 to 3. 5. Thermoformed product according to claim 4, characterized by a yellowing index less than 1.0.